A friend recently expressed concerns about her daughter’s shyness. When the girl’s first-grade teacher asked the kids to go around and say their favorite color, my friend’s daughter replied, “I’m sorry, that’s private.”

I’m sure her teachers and parents have some frustration ahead of them, but my first reaction was to think of ways she could teach some of this reticence to her peers. Indeed, many parents are wondering: How do we teach our kids to keep anything to themselves in a world where the payoff for sharing is so clear and enticing?

It is often said that kids these days grow up online so they just don’t think of privacy in the same way that adults do. But this masks an important element of their decisions. Divulging our most personal thoughts, the most intimate details of our lives, pictures of everything we hold near and dear — all of that is instantly rewarded today.

And adults are hardly immune to the siren call of retweets, Facebook likes and Web site hits. If you want to know why a woman might send out thousands of messages to the world about her battle with cancer (as New York Times columnist Bill Keller and his wife, Emma Keller, a columnist for The Guardian, did recently), it’s probably because she likes the feedback. Otherwise, presumably, she’d write a diary.

This is not an entirely new phenomenon. Actresses before Lena Dunham were offered praise for taking their clothes off on screen. But now they can claim that it’s all in the name of “realism” and land the cover of Vogue for their refreshing honesty. When a reporter recently questioned whether we really needed to see that much of Dunham, it seemed like Hollywood and half the Internet leapt to her defense. The more she takes off, the more she is to be praised.

Indeed, one can even be a savvy journalist and find oneself revealing too much. KJ Dell’Antonia, a New York Times blogger, last week lamented writing a piece for Slate a few years ago about the enormous difficulties she had after adopting her youngest child. In fact, she wrote that in the initial weeks after the adoption, she “did not love” the child. Now they are a happy family, but her children have found that article and Dell’Antonia’s regrets are great. The article, and especially its personal-confession headline, were, as she calls them, “click-bait.” And who among us can resist a few more clicks?

We know that kids see this inclination and imitate it. Wendy Mogel, a clinical psychologist, says she often talks to mothers about the example they are setting. “If you post pictures of your kids (no matter how darling) on Facebook or have a ‘tell nearly all’ mommy blog (no matter how relieving, illuminating and helpful to other parents), you’re inviting your kids to post and show and tell themselves.”

But it’s not just following their parents’ example that is making young people overshare, says Mogel, who is author of “The Blessing of a Skinned Knee.” “From the time they are young, kids are getting a lot of shallow praise,” she says. Kids who grow up earning “participation trophies” and easy compliments intended to boost their self-esteem can see feedback from Facebook and Instagram as a “fix” to get a “little ego boost.” “If kids don’t feel that they have other sources of satisfaction and pride,” she says, they can simply resort to social networking as a cheap way of earning praise.

And this inclination follows them into young adulthood, says Christine Whelan, author of “Generation WTF.” Not only are millennials tempted to spend too much time “narrating life rather than living it,” Whelan also worries that young adults’ need to “check to see how many ‘likes’ they get is not healthy.”

As Whelan rightly notes, “Not everything of value is meant to be shared publicly. The earlier we can teach that to our kids, the better, because everything in the online world is going to entice them in the other direction.”